Form factor and wire management. It sure is nice not having a single sata cable in my whole tower. NVMe is signficiantly faster than 2.5in SSD but most users won't notice the difference as it isn't night and day difference like platter to SSD was.After I looked around, for my use I found no reason to upgrade from a good SATA SSD to a NVME, but I'm also frugal, so it takes a bit to convince me.